West German Offenlegungsschrift No. 1,931,180 discloses a method for making cages for rolling bearings and in accordance with the method disclosed therein, the rolling element pockets are punched out by means of an appropriate die from a strip of sheet metal or the like. In a subsequent processing step, the axially extending surfaces of the cross pieces defining the rolling element pockets are bevelled by stamping with a die to adjust the width of the pocket to the desired dimensions. The stamping operation produces compaction and densification of the material and, hence, the danger of cracking or fissures developing in this area is relatively small. The corner regions of the pockets, however, are relatively sensitive points resulting from the bending stress which occurs when the strip material is formed into a ring-shaped cage and when the cage is under load during operation in a roller bearing. These areas, thus, tend to develop cracks or fissures which can lead to failure of the cage. Even if the cage does not fail, it has been found that the cage will be distorted by internal stresses which produces failure of the roller bearing.
In accordance with another known process disclosed in West German Pat. No. 1,066,978, the surfaces of the pocket defining the contact areas are also densified when the dimensions of the pockets are calibrated. In this instance, it is necessary to apply pressure on the contact surfaces by means of a wedge-shaped die to expand the rolling element pocket. Here again, even though the contact surfaces for the rolling elements according to this process acquires a surface which meets high expectations and which is not subject to the danger of cracking, the material of the cage in the corner area of the pockets is subjected to considerable stretching. Because the structure is relatively weak, the formation of cracks and fissures is, therefore, predestined.